Coronary artery disease (CAD) affects millions of Americans, making it the most common form of heart disease. CAD most often results from a condition known as atherosclerosis, wherein a waxy substance forms inside the arteries that supply blood to the heart. This substance, called plaque, is made of cholesterol, fatty compounds, calcium, and a blood-clotting material called fibrin. As the plaque builds up, the artery narrows, making it more difficult for blood to flow to the heart. As the blockage gets worse, blood flow to the heart slows, and a condition called angina pectoris, or simply angina, may develop. Angina is like a squeezing, suffocating, or burning feeling in the chest. The pain usually happens when the heart has an extra demand for blood, such as during exercise or times of emotional stress. In time, the narrowed or blocked artery can lead to a heart attack. A number of medicines can be used to relieve the angina pain that comes with CAD, but these medicines cannot clear blocked arteries. A moderate to severely narrowed coronary artery may need more aggressive treatment to reduce the risk of a heart attack.
Balloon angioplasty is a technique for mechanically widening narrowed or obstructed arteries, the latter typically being a result of atherosclerosis. An empty and collapsed balloon on a guide wire, known as a balloon catheter, is passed into the narrowed locations and then inflated to a fixed size using water pressures some 75 to 500 times normal blood pressure (6 to 20 atmospheres). The balloon is carefully inflated, first under low pressure, and then under higher pressure, until the narrowed area is widened. The balloon inflation crushes the fatty deposits it expands against, opening up the blood vessel for improved blood flow. The balloon is then deflated and withdrawn. Although the narrowing is improved in a majority of patients following balloon dilation, over time, the artery can again become narrow in as many as 15% to 20% of cases, requiring further balloon dilation. A stent may or may not be inserted at the time of balloon dilation to ensure the vessel remains open.
Percutaneous coronary intervention (PCI) is a therapeutic procedure to treat the stenotic (narrowed) coronary arteries of the heart due to CAD. These stenotic segments are caused by the buildup of plaque that forms due to atherosclerosis. PCI is usually performed by an interventional cardiologist.
PCI includes the use of balloons, stents, and atherectomy devices. PCI is accomplished with a small balloon catheter inserted into an artery in the groin or arm, and advanced to the narrowing in the coronary artery. The balloon is then inflated to enlarge the narrowing in the artery. When successful, PCI allows more blood and oxygen to be delivered to the heart muscle and can relieve the chest pain of angina, improve the prognosis of individuals with unstable angina, and minimize or stop a heart attack without having the patient undergo open heart coronary artery bypass graft (CABG) surgery.
Balloon angioplasty is also called percutaneous transluminal coronary angioplasty (PTCA). Both PCI and PTCA are non-surgical procedures. Balloon angioplasty can also be used to open narrowed vessels in many other parts of the body. Peripheral angioplasty (PA) refers to the use of a balloon to open a blood vessel outside the coronary arteries. It is commonly done to treat atherosclerotic narrowing of the abdomen, leg, and renal arteries. PA can also be done to treat narrowing in veins. Often, PA is used in conjunction with peripheral stenting and atherectomy. For example, doctors can perform carotid angioplasty to open narrowed carotid arteries, which are the arteries that supply blood to the brain. A stroke most often occurs when the carotid arteries become blocked and the brain does not get enough oxygen. Balloon angioplasty can also be performed in the aorta (the main artery that comes from the heart), the iliac artery (in the hip), the femoral artery (in the thigh), the popliteal artery (behind the knee), and the tibial and peroneal arteries (in the lower leg). The use of fluoroscopy assists the doctor in the location of blockages in the coronary arteries as the contrast dye moves through the arteries. A small sample of heart tissue (biopsy) may be obtained during the procedure to be examined later under the microscope for abnormalities.
A cutting balloon (CB) is an angioplasty device used in PCI and PTCA and is a proven tool for the mechanical challenges of complex lesions that are often resistant to conventional balloon angioplasty. A CB has a special balloon with small blades that are activated when the balloon is inflated. The CB typically has three or four atherotomes (microsurgical blades) bonded longitudinally to its surface, suitable for creating discrete longitudinal incisions in the atherosclerotic target coronary segment during balloon inflation. Cutting balloon angioplasty (CBA) features three or four atherotomes, which are 3-5 times sharper than conventional surgical blades. The atherotomes, which are fixed longitudinally on the outer surface of a non-complaint balloon, expand radially and deliver longitudinal incisions in the plaque or target lesion, relieving its hoop stress. With the CBA, the increase in the vessel lumen diameter is obtained in a more controlled fashion and with a lower balloon inflation pressure than PCI and PTCA procedures utilizing conventional balloons. This controlled dilation could reduce the extent of vessel wall injury and the incidence of restenosis.
The advantage of CBA is its ability to reduce vessel stretch and vessel injury by scoring the target coronary segment longitudinally rather than causing an uncontrolled disruption of the atherosclerotic plaque or target lesion. The atherotomes deliver a controlled fault line during dilation to ensure that the crack propagation ensues in an orderly fashion. The CB also dilates the target vessel with less force to decrease the risk of a neoproliferative response and restenosis. The unique design of the CB is engineered to protect the vessel from the edges of the atherotomes when it is deflated. This minimizes the risk of trauma to the vessel as the balloon is passed to and from the target coronary segment. With CBA, balloon inflation pressures can still range between 14-16 atmospheres, though lower inflation pressures are recommended.
Angioplasty balloons that employ a woven mesh, cutting strings, or wires are also known in the art. These balloons have been shown to be more flexible and safer than balloons employing cutting blades and edges. The scoring elements can, for example, be in the form of a single wire or a plurality of wires wrapped around a dilation balloon in a helical configuration. Other angioplasty cutting balloon catheter assemblies have a catheter equipped with an inflatable balloon with an interior cavity and an expandable covering around the balloon. The expandable covering may be in the form of a mesh coating having a cross-hatched pattern. The mesh coating may be made of plastic or metal fibers, where at least some of the fibers have cutting edges. In operation, the cutting edges abrade the stenosis, plaque, or lesions along the vessel walls when the catheter assembly is reciprocally moved longitudinally or rotationally after inflation of the balloon.